In chemical engineering heat calculations, which unit – joule or calorie – has a more understandable physical meaning for calculations?
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Joules and calories are both units of heat. In chemical engineering heat calculations, it is necessary to determine which units to use, so that the expressions are more convenient and easier to understand. I often see values expressed in terms of calories, but the units used for heat of vaporization and specific heat are J and KJ. As a newcomer to this field, I’m not very familiar with these concepts.
Currently, there are many units of kilocalories used, which makes it very convenient for converting steam volume or condensate volume.
It’s all the same; it’s just a matter of making the conversions. Check whether the project requires the International System of Units – if not, use J and kJ instead
Joules are commonly used; most logistics applications make use of joules. However, in heat exchange applications, kilocalories are typically used, such as in furnaces and heat exchangers
Standardized unit system~~~joule
J and KJ are commonly used in books to correspond with the International System of Units. However, in engineering, it is generally expressed in kilocalories, Kcal. Why? ? If the specific heat of water is expressed in joules, it is 4.2 KJ/°C·kg; but if it is expressed in kilocalories, it is 1 kcal/°C·kg. If you’re asked how much heat is needed to raise the temperature of 1 kilogram of water by 25°C, you can instantly answer 25 calories, but what about trying it using the International System of Units? Go and calculate it yourself~ So, for convenience in engineering diagrams, heat is expressed in kilocalories, which makes conversion easier.
Another point is that different industry segments use different standard units: in the large-scale chemical industry, kilocalories are more commonly used； In the petrochemical industry, MJ is used quite frequently.